According to the World Health Organization, tooth decay is one of the world's most prevalent health problems. It has been estimated that 90% of people in the United States have at least one cavity. Children and senior citizens are the two groups of people at highest risk. Dental resin restorations represent a significant market, but over 60% of all restorative dentistry is for the replacement of restorations. Placement of resin restorations is technique sensitive and, therefore, must be placed properly to deliver the best health care to patients. The most common cause of failure of resin restorations is secondary caries (tooth decay) due to micro-leakage around the restoration, followed by restoration fracture, and marginal defects. These failures may be due to the fact that the resin restoration was inadequately polymerized and did not reach its intended physical properties.
Dental students, dentists and dental auxiliaries are evaluated on their ability to prepare teeth and on the final restoration of the tooth. However, the ability of the operator (for example, a dentist, or a dental student) to deliver sufficient useful curing energy to adequately cure a restoration is not readily measurable, and it is not feasible to detect visually or tactily if the resin restoration is adequately cured.
Inadequately cured resins will result in reduced physical properties of the restoration, reduced bond strengths, increased wear and breakdown at the margins of the restoration, decreased biocompatibility, and increased DNA damage from the leachates. These leachates can include bisphenol A diglycidylether methacrylate (Bis-GMA), tetraethyleneglycol dimethacrylate (TEGDMA), 1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4-trimethylhexane (UDM), 2,2-bis(4-(2-Methacryloxyethoxy)phenylpropane (bis-EMA), and bisphenol A with the total monomer of BisGMA and TEGDMA eluted reported to range from 8.75 to 27.97 ppm. In vitro studies have shown that resin components can evoke either immunosuppression or immunostimulation on mitogen-driven proliferation of purified T-lymphocytes and spleen cells. Conversely, too much curing energy delivered to the restoration may cause an unnecessary and unacceptable temperature increase in the tooth and surrounding oral tissues.